Process for the preparation of belta2-oxazoline



United States Patent PRGCESS FOR THE PREPARATION OF A -OXAZOLINELawrence G. Hess, Charleston, W. Va., assignor to Union CarbideCorporation, a. corporation of York No'Drawing. Application June 5, 1953Serial No: 359,970

Claims. (Cl. 260-307) This invention relates to a: process for thepreparation of A -oxazoline, and. more particularly to a process for thepreparation of ri -oxazoline by the dehydration ofN-(Z-hydroxyethyl)formamide.

A convenient and economical method for the preparation of A -oxazolinehas long been lacking in the art, and, inasmuch as A -oxazoline and itsderivatives possess potentialities as solvents, chemical intermediates,textile finishing agents, vulcanization accelerators, and localanesthetics, a suitable method for its preparation is of particularinterest.

Accordingly it is an object of this invention to provide a relativelyinexpensive process for the preparation of A -oxazoline.

Furthermore, it is an object of this invention to provide a process forthe preparation of M-oxazoline which does not involve the use of theexpensive and corrosive reagents such as those employed by the prior artinvestigators.

Heretofore, the methods for the preparation of A oxazoline have not beenfeasible for large scale industrial operations. The prior artinvestigators prepared A oxazoline by dehydrochlorinatingbeta-chloroethyl formamide with aqueous alkali but the process wasaccompanied by decomposition of the desired product, thus giving pooryields of the A -oxazoline.

This invention, however, is directed to a process for the preparation ofA -oxazoline which comprises heating N- (Z-hydroxyethyDformamide at anelevated temperature. This invention is also directed to a process forthe preparation of d -oxazoline, which comprises heatingN-(2-hydroxyethyl) formamide in the presence of a dehydrating agent.More particularly, this invention contemplates the use of dehydratingagents, such as, for example, Super Filtrol (diatomaceous earth),sulfuric acid, aluminum oxide and iron oxide.

The reaction, either in liquid phase or vapor phase, whereby A-oxazoline is obtained in accordance with this invention may be writtenas follows:

A CH2CH2 HOCHaCHzNH-(i-H The temperature of the dehydration step iscarried out at a temperature in the range 150 C. to about 250 C. asshown in the following examples.

Inasmuch as A -oxazoline reverts readily to N-(2-hy- 2,844,589 PatentedJuly 22, 1958 Example: I

Equimolecular quantities of monoethanolamine and formic acid were addedvto alive-liter glasskett-le equipped with a stirrer, thermometer andreflux. condenser The kettle was immersed in a cooling bath and'thetemperature of the reaction was maintained at 50-55 C. The

, crude N-(2-hydroxyethyl)formamide formed was then distilled through aglass still column packed with stainless steel sponge at a kettletemperature of 160-200 C. under an absolute pressure of 5-20 mm. ofmercury and the low-boiling product was collected in cold traps immersedin carbon dioxide-acetone solution. One portion of this cold trapmaterial was stored for a period of two days and was found to contain75% N-(Z-hydroxyethyl) fonnamide. Another portion of this material wasextracted with carbon tetrachloride and the extract gave upondistillation a fraction boiling at 94.6-95 C. and having a molecularweight of 71. This fraction contained 50.8%, C.; 7.6%, H; 19.1%, N;which corresponds to the theoretical elemental analysis of A -oxazoline,and gave the mass spectrometer pattern predicted for A oxazoline. Fromits reversion to N-(2-hydroxyethyl) formamide and the foregoinganalytical data, the material was determined to be A -oxazoline.

Example II When 252 grams of N-(Z-hydroxyethyl)formamide were passedover aluminum oxide at 248-253 C. (under 10 mm. of mercury, absolutepressure) in an essentially vapor phase process, approximately 23 gramsof A -oxazoline were produced. The product when analyzed massspectrometrically gave the same pattern as the material produced inExample 1. Approximately 32 percent of the N-(Z-hydroxyethyl)formamidewas converted, 36 grams of monoethanolamine being produced in additionto the A -oxazoline.

Example III When 230 grams of N-(Z-hydroxyethyDformamide were heatedwith 35 grams of Super Filtrol (diatomaceous earth) at 198 C. (45 mm. ofmercury) for a period of about two hours, the aqueous solution collectedin cold traps was found to contain 22 grams of A -oxazoline agree ingmass spectrometrically with that produced in Example I. TheN-(Z-hydroxyethyl)formamide conversion was 22 percent, the yield ofmonoethanolamine being 10 percent based on the amount ofN-(2-hydroxyethyl)formamide charged.

Example IV Heating 295 grams of N-(2-hydroxyethyl)formamide with 0.05gram of sulfuric acid at -160 C. (6 mm. of mercury) gave 6 grams of A-oxazoline over a period of 3.5 hours. The dehydration was accompaniedby de composition to monoethanolamine, the yield being 48- percent.

3 Example V Two hundred and thirty-three grams ofN-(Z-hydroxyethyl)formamide were heated at 180 C. at 20 mm. of mercurypressure in the presence of 12 grams of iron oxide in a laboratory stillkettle. Twenty grams of A oxazoline, were collectedas an aqueoussolution in cold traps after a period of-3.5 hours. The product obtainedby extraction with carbon tetrachloride gave the same rnassspectrometric pattern as the material isolated in Example I. About 24percent of the N-(Z-hydroxyethyl) formamide was converted. Approximately21 grams of monoethanolamine was formed.

' I claim:

I 1. A process for the preparation of A -oxazoline which comprisesheating N-(Z-hydroxyethyDformamide at an elevated temperature in therange 150 C. to 250 C. under reduced pressures in the presence of adehydrating agent selected from the group consisting of aluminum oxide,iron oxide, sulfuric acidand diatomaceous earth and recovering the A-oxazoline thus: produced.

' 2. A process for the preparation of A -oxazoline which comprisesheating N-(2-hydroxyethyl)formamide at an elevated temperature in therange 150 C. to 250 C.

'4. under reduced pressures in the presence of aluminum oxide andrecovering the A -oxazoline thus'produced.

3. A process for the preparation of A -oxazoline which comprises heatingN-(Z-hydroxyethyl)formamide at. an elevated temperature in the range 150C. to 250 C. under reduced pressures in the presence of iron oxide andrecovering the A -oxazoline thus produced.

4. A process forthe preparation of A -oxazoline which comprises heatingN-(Z-hydroxyethyl)formamide at an elevated temperature in the range 150C. to 250 C. under reduced pressures in the presence of sulfuric acidand recovering the A -oxazoline thus produced.

5. A process for the preparation of A -oxazoline which comprises heatingN-(Z-hydroxyethyl)formamide at an elevated temperature in the range 150C. to 250 C. under reduced pressures in the presence of diatomaceousearth and recovering the A -oxazoline thus produced.

References Cited in the file of this patent Wenker: J. Am. Chem. Soc,vol. 57, pp. 1079-80 (1935).

Wiley et al.: Chem. Reviews, vol. 44, pp. 4524 (1949).

1. A PROCESS FOR THE PREPARATION OF $2-OXAZOLINE WHICH COMPRISES HEATINGN-(2-HYDROXYETHYL FORMAMIDE AT AN ELEVATED TEMPERATURE IN THE RANGE150*C. TO 250*C. UNDER REDUCED PRESSURES IN THE PRESENCE OF ADEHYDRATING AGENT SELECTED FROM THE GROUP CONSISTING OF ALUMINUM OXIDE,IRON OXIDE, SULFURIC ACID AND DIATOMACEOUS EARTH AND RECOVERING THE$2-OXAZOLINE THUS PRODUCED.